These days, some people are discussing the feasibility of an Indo-Japanese alliance. Click here for an excellent article by Rajeev Srinivasan on the topic. And here is my take on the whole issue:
China does not want Japan (or India, or any other country) to become politically or militarily powerful. Against Japan, it has a good argument - the rape of Nanjing. It will oppose Japan vigorously if it feels that Japan is getting a bit too "aggressive". The massive protests we saw in front of the Japanese embassy in China were meant to jeopardise Japan's plans of gaining a permanent Security Council seat. We should expect China to oppose us too, since we are a rising power.
An alliance of some sort with Japan will be beneficial for India in many ways:
1) Japan is not a terrorist nation. So the move will not backfire on us like the support for the Taliban did on the US, or the support of the LTTE did for us. It will certainly not isolate us internationally. Moreover, we can do to China what they did to us using Pakistan.
2) The Chinese have a large and seemingly powerful navy (with lots of submarines). I use the word "seemingly" because not much is known about the kind of training they recieve, and their equipment is mostly outdated.
Peoples Liberation Army Navy - Intoduction
Peoples Liberation Army Navy - Ships
On the other hand, the Japanese have one of the most powerful and modern navies in the world. In a war, the Japan Maritime Self Defence Force (JMSDF) will defeat the People's Liberation Army's Navy (PLAN).
Japan Maritime Self Defence Force - Introduction
Japan Maritime Self Defence Force - Ships
Japan Self Defence Force PR video. Highly recommended. From Bharat Rakshak
The Indian Navy (IN) is not very well equipped and may not survive a concerted PLAN campaign. The delays in new acquisitions are adversely affecting its fighting ability. While The IN leads the PLAN when it comes to electronics, command and control, training, tactics, etc, the sheer numbers of PLAN warships will most likely overwhelm the Indian Navy in the near future.
Indian Navy - Introduction
Indian Navy - Ships
Thus, the JMSDF will be a powerful friend to have in times of a crisis. It may not need to fight the PLAN, just tying down enough PLAN resources will do.
3) The Japanese Army however, is quite small, and its ability to fight its Chinese and North Korean counterparts, especially if they use human-wave attacks is very limited. In such a scenario, the Indian Army, which is very well trained, well equipped with the latest Israeli, Russian, Indian, and American (to a small extent) equipment, and very high on morale, will be a perfect foil for China’s bloated People’s Liberation Army (PLA). Once again, it does not actually need to fight the PLA – mobilisation on the eastern border to tie down most Chinese troops will do. The PLA is certainly not interested in fighting the IA, which is a very different force from what it was in 1962.
People’s Liberation Army
Japan Ground Self Defence Force
4) As far as Air Forces are concerned, the (PLAAF) is very large, but notoriously ill-trained and works with obsolete equipment. The Indian Air Force (IAF), on the other hand is very well trained (as is evident from the results of the Indo-US Cope-India 2004 exercise) and has a lot of high technology equipment at its disposal (though most of the workhorse MiG-21s are in dire need of upgrades). How the IAF and PLAAF would perform against each other is hard to tell. However, if the Japan Air Self Defence Force (JASDF) and IAF launch an attack on China on two fronts, the PLAAF will not be able to cope.
People's Liberation Army Air Force
Indian Air Force
Japan Air Self Defence Force
5) Japan is the second largest economy in the world, and is industrial capabilities are one of the most advanced in the world.
List of countries by GDP (nominal)
An alliance with Japan will undoubtedly strengthen India’s industrial capabilities, especially our manufacturing sector.
Thus, an Indian alliance with Japan will hugely benefit the two countries militarily, and economically, and check China’s rising power in the region.